Microelectronic elements such as semiconductor chips are commonly provided with elements that facilitate connection to other larger circuits. For example, a semiconductor chip is typically provided as a small, flat package having oppositely facing front and rear surfaces and contacts at the front surface. The contacts are electrically connected to numerous electronic circuit elements formed integrally within the chip.
Advances in semiconductor chip design and manufacture have led to semiconductor chips having a higher number and higher density of electrical contacts at finer and finer pitches. Such contacts on the chip may be joined by solder balls or other connectors to conductive elements on a facing surface of a motherboard, substrate, microelectronic assembly, another semiconductor chip, or larger package. Connecting high density contacts of such a microelectronic element to corresponding high density receiving elements on a facing surface can require a lot of precision, and cost investment as sometimes the contacts on surfaces of the microelectronic elements do not perfectly align with each other.